2-SUBSTITUTED OR NON-SUBSTITUTED-NON-THIAZALO [5,4-f] QUINALINE-8-CARBOXYLATES COMPOUNDS AND THEIR METHOD OF PREPARATION

ABSTRACT

A compound represented by the formula: WHEREIN R is a lower alkyl group, and R&#39;&#39; is a member selected from the group consisting of a hydrogen atom, a halogen atom, a lower alkyl group, a lower alkoxy group, a lower alkylthio group and a sulfhydryl group.

Unified Sfiates Patent 91 Dohmori et al.

[ Jan.30, 1973 [75] Inventors: Renzo Dohmori; Shizuo Kadoya; Isao Takamura; Yasuo Oshima; Takeo Naito, all of Tokyo-to, Japan [73] Assignee: Daiichi Seiyaku Co., Ltd., Tokyo-to,

Japan 22 Filed: Nov. 17, 1970 21 Appl. No.: 90,479

[30] I Foreign ApplicationPriority Data Nov.l7,l969 Ja an. ..-.....44 91946 [52] UQSJCI ..260/283 S, 260/287 R, 260/304,

I 1 260/306, 424/258 [51] Int. Cl. ..C07d 91/42 [58] Field of Search ..260/287, 283 S [56] References Cited UNITED STATES PATENTS 3,287,458 11/1966 Kaminsky el al. ..260/287R 4/1970 Kaminsky .260/287R 6/1970 Tull ..260/287X OTHER PUBLICATIONS Landquist, Chem. Abstr. Vol. 68, C01. 2839h, (1968).

Primary Examiner- Donald G. Daus Attorney-Sughrue, Roth'well, Mion, Zinn and Macpeak [57] ABSTRACT I A compound represented by the formula: RTS N l wherein R is a lower alkyl group, and R is a member selected from the group consisting of a hydrogen atom, a halogen atom, a lower alkyl group, a lower alkoxy group, a lower alkylthio group and a sulfhydryl group.

9 Claims, No Drawings Z-SUBSTITUTED OR NON-SUBSTITUTED-NON- THIAZALO [5,4-F] QUINALINE-B- CARBOXYLATES COMPOUNDS AND THEIR METHOD OF PREPARATION FIELD OF THE INVENTION This invention relates to novel thiazoloquinoline derivatives and to a method for preparing said compounds.

DETAILED DESCRIPTION OF THE INVENTION ll 011 BN 9 j co OR 4 wherein R represents a lower alkyl group and R represents a radical selected from the group consisting of a hydrogen atom, a halogen atom, a lower alkyl group, a lower alkoxy group, a, lower alkylthio group, and a sulfhydryl group.

The novel compounds of the present invention have excellent antibacterial activity especially against Grampositive bacteria. For instance, the anti-bacterial activity of ethyl 2-ethoxy-9-hydroxy-thiazolo[5,4-f]quinoline-8-carboxylate (A) was found to be more excellent than those of nalidixic acid (B) and sulfadimetoxine (C) which have been well known as representative synthetic antibiotics. The comparative test of these compounds was carried out with the Mueller Hinton medium under cultivation at 37C for 48 hours. The test results expressed as minimal inhibitory concentration (MIC) are tabulated in the following Table I.

According to the present invention, the compounds of Formula (I) can be prepared by the cyclization of benzothiazole derivatives (II). The reaction scheme is as follows:

in above scheme R and R have the same meaning as defined hereinabove. The cyclization reaction may be conducted by heating compound (II) at a temperature of between 150 and 300C in a suitable solvent such as Dowtherm, diethyl phthalate, dodecyl benzene or any other inert solvent having a highboiling point. The cyclization is usually complete enough by heating from ten to several tens hours. The reaction time, however, varies to some extent depending upon the particular type of starting material (11).

The starting material (11) used in above reaction is also a novel compound, which can be readily synthesized from the corresponding dialkyl ethoxymethylene malonate and 6-amino-benzothiazole derivatives.

The present invention will be more fully explained by reference to the following non-limiting examples.

EXAMPLE 1 Dowtherm A was heated in an oil bath at a temperature of 120C for 2 hours and allowed to cool. The solid that separated was collected and recrystallized from methanol to yield 18.0 g percent) of 6'-[bis(2,2- ethoxy-carbonyl )ethenylaminolbenzothiazole as colorless needles; m.p. ll7-1i9C.

Analysis Calculated for C, H, 0 N S: C, 56.23; H, 5.04; N, 8.75

Found: C, 56.08; H, 4.92; N, 8.74

EXAMPLE 2 A mixture containing 5.05 g of 2-chloro-6-[ bis(2,2ethoxycarbonyl) ethenylaminolbenzothiazole and 50 ml of Dowtherm A was heated at temperatures of 235-240C for 10 minutes and at 240-250C for 30 minutes and then allowed to cool. The solid that separated was collected and recrystallized from dimethylformamide to give 4.01 g (86 percent) of ethyl 2-chloro9-hydroxythiazole[5,4-f]quinoline-8-carboxylate as a yellow powder; m.p. 300C.

Analysis Calculated for C H O N SCl: c, 50.57; 11,294; N, 9.08 FoundzC,50.86;H,2.95;N,9.37

The intermediate 2-chloro-6-[bis(2,2-ethoxycarbonyl)-ethenyl-amino]benzothiazole was prepared as follows: A mixture of 18.5 g of 6-amino-2- chlorobenzothiazole and 21.6 g of diethyl ethoxymethylenemalonate in 37 ml of dimethylformamide was heated at temperatures of 100C for 1 hour and allowed to cool. Methanol was added to the reac- Recrystallization from methanol gave 27.5 g (78 percent) of 2-chloro-6-[bis(2,2-ethoxycarbonyl)ethenylaminolbenzothiazole as colorless needles; mp l60162C.

Analysis Calculated for Found: C, 51.03; H, 4.20; N, 8.17

' EXAMPLE 3 Eighty milliliters of Dowtherm A was heated to reflux and to it was added 10.0 g of 2-methyl-6-[ bis(2,Z-ethoxycarbonyl)ethenylamino]benzothiazole dissolved in 20 ml of warm Dowtherm A. The reaction mixture was then heated at temperatures of 250255 C for 10 minutes and allowed to cool. The solid that separated was collected and recrystallized from dimethyl-formamide to yield, as colorless powder, 5.25 g (61 percent) of ethyl-9-hydroxy-2-methylthiazolo[ 5,4-f]quinoline-8-carboxy1ate, m.p. 293C (decomp) Analysis Calculated for C H O N SJMH O: C, 57.42; H, 3.61; N, 9.57 Found: C, 57.47; H, 3.90; N, 9.87

The intermediate 2-methyl-6-[bis(2,2 ethoxycarbonyl-)ethenylamino]benzothiazole was prepared as follows: A mixture of 9.89 g of 6-amino-2-methylbenzothiazole and 12.96 g of diethyl ethoxymethylenemalonate in 60 ml'of Dowtherm A was heated at temperatures of 100l20C for hours and allowed to cool. The crystals that separated was collected and recrystallized from. acetone to yield 2- EXAMPLE4 A mixture containing 1.92 g of 2-ethoxy-6-[bis(2,2- ethoxycarbonyl)-ethenylaminoIbenzothiazole and 19 ml of Dowtherm A was refluxed for 15 minutes and allowed to cool. The solid that separated was collected and recrystallized from dimethylformamide to yield 1.45 g (86 percent) of ethyl-2-ethoxy-9-hydroxythiazolo[5,4-f]quinoline-8-carboxylate as colorless needles melting above 300C.

Analysis Calculated for C,,,H O N S: C, 56.59; H, 4.43; N, 8.80 Found:C,56.43;H,4.21;N,8;96 I

The intermediate 2-ethoxy'-6 [bis(2,2-ethoxycarbonyl)-ethenylaminolbenzothiazole was prepared as follows: A mixture of 1.95 g of 6-amino-2-ethoxybenzothiazole and 2.16 g of diethyl ethoxymethylenemalonate in 4 ml of dimethylformamide was heated at a temperature of 95C for 1 hour and allowed to cool. Ethanol was added to the mixture and the solid that separated as collected. Recrystallization from ethanol gave 2.41 g ('66 percent) of 2-ethoxy-6-[ bis( 2,2-ethoxycarbonyl)ethenylamino]benzothiazole melting at 1 l5-1 16C as colorlessneedles.

Analysis Calculated for C H, O,,N,S: C, 56.03; H, 5.53; N, 7.69 Found:C, 56.30; H,5.25; N, 7.65

EXAMPLE 5 A mixture containing 5.0 g of 2-methylthio-6-[ bis(2,2-ethoxy-carbonyl)ethenylamino]benzothiazole and 50 ml of Dowtherm A was heated at temperatures of 240245C for 22 minutes and allowed to cool. Acetone was added to the mixture and the solid that separated was collected and recrystallized from dimethyl sulfoxide. There was thus obtained ethyl-9- hydroxy-Z-methylthiothiazolo[ 5,4-t1quinoline-8-car-v boxylate, melting above 300C, as pale yellow needles, 3.68 g (84 percent).

Analysis Calculated for c,,H,,o,N,'s,; C, 52.48;H, 3.78;N, 8.75 Found: C, 52.19; H, 3.67; N, 8.94

The intermediate 2methylthio-6-[bis(2,2-ethoxycarbonyl)-ethenyl-amino]benzothiazole was prepared as follows: A mixture of 15.0 g of 6-amino-2- methylthiobenzothiazole and 16.6 g of diethyl ethoxymethylenemalonate in ml of Dowtherm A was heated at temperatures of 105-1 10C for 2 hours and allowed to cool. The solid that separated was recrystallized from acetone to give 21.8 g percent) of 2- methylthio-6-[bis(2,2-ethoxycarbonyl). ethenylamino]benzothiazole melting at 132134C as colorless needles.

Analysis Calculated for C H, O NS C, 52.44; H, 4.95; N, 7.65 Found: C, 52.45; H, 5.08; N, 7.80

EXAMPLE 6 A A mixture of 5.0 g of 2'-mercapto-6-[bis(2,2-ethoxycarbonyl) ethenylaminolbenzothiazole in 50 m1 of Dowtherm A was heated at temperatures of 220-240 "C for 40 minutes and allowed to cool. The solid that separated was collected and recrystallized from dimethylformamide to yield 2.50 g (58 percent) of ethyl-9-hydroxy-2-mercaptothiazolo[5,4-f]quinoline-8 -carboxylate melting above 300C as a'yellow powder. Analysis Calculated for C H O N S C, 50.95; H, 3.29; N, 9.15 Found: C, 50.67; H, 3.58; N, 9.42

The intermediate 2-mercapto-6-[bis(2,2-ethoxycarbonyl)-ethenylaminolbenzothiazole was prepared as follows: A mixture of 17.8 g of 6-amino-2-mercaptobenzothiazole and 21.6 g of diethyl ethoxymethylenemalonate in ml of Dowtherm A was heated at temperatures of -130C for 1% hours and recrystallized from dimethylformamide to give 279g (81 percent) of 2-mercapto-6-[bis(2,2-ethoxycarbonyl)ethenylaminoI-beniothiazole, melting at 255-256C (decomp.), as a pale yellow powder. Analysis Calculated for C, H O N S,: C, 51.12; H, 4.58; N, 7.95 Found: C, 50.83; H, 4.70; N, 8.11

What is Claimed is:

1. A compound represented by the formula:

wherein R is a lower alkyl group, and R is a member selected from the group consisting of a hydrogen atom, a halogen atom, a lower alkyl group, a lower alkoxy group, a lower alkylthio group and a sulfhydryl group.

2. The compound of claim 1 which is ethyl-9-l'1ydroxythiazolo-[S ,4-f]-quinoline-8-carboxylate.

3. The compound of claim 1 which is ethyl-2-chloro- 9-hydroxythiazole-[ 5 ,4-f1-quinoline-8-carboxylate.

4. The compound of claim 1 which is ethyl-9-hydroxy-2-methylthiazolo-[5,4-f]-quinoline-8-carboxylate.

5. The compound of claim 1 which is ethyl-Z-ethoxy- 9-hydroxythiazolo-[5,4-f]-quinoline-8-carboxylate.

6. The compound of claim 1, which is ethyl-9- hydroxy-2mercaptothiazolo-[5,4-fl-quinoline-8-carboxylate.

7. A process for preparing thiazolo[5,4-f]quinoline compounds represented by the formula:

I OH N l COOR wherein R is a lower alkyl group and R is a member selected from the group consisting ofa hydrogen atom, a halogen atom, a lower alkyl group, a lower alkoxy group, a lower alkylthio group and a sulfhydryl group, which comprises heating a benzothiazole compound represented by the following formula:

N OR A 

1. A compound represented by the formula: wherein R is a lower alkyl group, and R'' is a member selected from the group consisting of a hydrogen atom, a halogen atom, a lower alkyl group, a lower alkoxy group, a lower alkylthio group and a sulfhydryl group.
 2. The compound of claim 1 which is ethyl-9-hydroxythiazolo-(5, 4-f)-quinoline-8-carboxylate.
 3. The compound of claim 1 which is ethyl-2-chloro-9-hydroxythiazole-(5,4-f)-quinoline-8-carboxylate.
 4. The compound of claim 1 which is ethyl-9-hydroxy-2-methylthiazolo-(5,4-f)-quinoline-8-carboxylate.
 5. The compound of claim 1 which is ethyl-2-ethoxy-9-hydroxythiazolo-(5,4-f)-quinoline-8-carboxylate.
 6. The compound of claim 1, which is ethyl-9-hydroxy-2-mercaptothiazolo-(5,4-f)-quinoline-8-carboxylate.
 7. A process for preparing thiazolo(5,4-f)quinoline compounds represented by the formula: wherein R is a lower alkyl group and R'' is a member selected from the group consisting of a hydrogen atom, a halogen atom, a lower alkyl group, a lower alkoxy group, a lower alkylthio group and a sulfhydryl group, which comprises heating a benzothiazole compound represented by the following formula: wherein R and R have the same meaning as defined above, in an inert solvent for a period of time and at a temperature sufficient to cyclize said benzothiazole compound.
 8. The process of claim 7 wherein the temperature varies from 150* to 300*C. 